1. Field of the Invention
The present invention relates to a medical image processing apparatus and a method for controlling the medical image processing apparatus and, more particularly, to a medical image processing apparatus for performing processing on a picked-up image of a living tissue inside a body cavity and a method for controlling the medical image processing apparatus.
2. Description of the Related Art
Endoscope systems configured to include an endoscope, a medical image processing apparatus, and the like have been widely used. More specifically, an endoscope system is configured to include, for example, an endoscope which is composed of an insertion portion to be inserted into a body cavity of a subject, an objective optical system arranged at a distal end portion of the insertion portion, and an image pickup portion that picks up an image of an object inside the body cavity formed by the objective optical system and outputs the image as image pickup signals and a medical image processing apparatus that performs processing for displaying the image of the object on a monitor or the like as a display portion on the basis of the image pickup signals. The endoscope system with the above-described configuration enables various findings by observing, for example, mucosal color tone, shape of a lesion, a microstructure on a mucosal surface, and the like in a digestive tract mucosa of a stomach or the like.
Studies on a technology called CAD (computer aided diagnosis or computer aided detection) as in, for example, Kenshi Yao et al., “Sokiigan no bisyokekkankochikuzo niyoru sonzai oyobi kyokaishindan (Diagnosis of Presence and Demarcations of Early Gastric Cancers Using Microvascular Patterns),” Endoscopia Digestiva, Vol. 17, No. 12, pp. 2093-2100, 2005, have been in progress in recent years. The technology enables finding and diagnosing a lesion by extracting, at a mucosal epithelium inside a body cavity, a region where a microvascular structure or a pit (gland opening) structure exists on the basis of image data obtained through pickup of an image of an object by an endoscope or the like and presenting a result of extracting the region.
Additionally, a technique for extracting a blood vessel candidate region as a region where a blood vessel may exist on the basis of image data obtained through pickup of an image of an object by an endoscope or the like and obtaining a result of detecting a blood vessel region as a region where a blood vessel can be regarded as actually existing by performing correction processing such as region expansion or reduction on a result of extracting the blood vessel candidate region is disclosed in, for example, Toshiaki Nakagawa et al., “Recognition of Optic Nerve Head Using Blood-Vessel-Erased Image and Its Application to Simulated Stereogram in Computer-Aided Diagnosis System for Retinal Images,” IEICE Trans. D, Vol. J89-D, No. 11, pp. 2491-2501, 2006.
Hemoglobin in erythrocyte has strong absorption characteristics in a band of G (green) light among bands of wavelengths constituting RGB light. For the reason, a density value of G (green) in a region where a blood vessel exists tends to be lower than a density value of G (green) in a region where no blood vessel exists in, for example, image data obtained when an object including the blood vessel is irradiated with RGB light. For example, as a technique which takes the tendency into account, a technique is known for extracting a blood vessel candidate region by applying a band-pass filter to image data obtained through pickup of an image of an object by an endoscope or the like.